Electrical connector



Se t. 4, 1956 F. K. KNOHL ELECTRICAL CONNECTOR Filed March 5, 1953 an"1L3 United States Patent ELECTRICAL CONNECTOR Friedrich Karl Knohl,Chicago, Ill., assignor to Illinois Tool Works, Chicago, 111., acorporation of Illinois Application March 5, 1953, Serial No. 340,513

3 Claims. (Cl. 339-192) This invention is concerned generally with anelectric socket construction and more particularly with a clip forming afemale electrical connector and its cooperating insulating housing.

In many applications of plug-and-socket electrical connectors such asfor ranges, clothes dryers, water heaters, and many other uses, rathersubstantial currents must be handled. In many prior connectors,substantially only line contact has been made between the male andfemale connectors. This gives rise to heavy current densities causingoverheating of the connectors, burning and pitting along the lines ofcontact, and generally short service life.

All electrical connectors must have some sort of insulated housings andmust be mounted in such housing in some manner. The best insulationsfrom the standpoint of electrical non-conductivity and heat resistanceare ceramics. Unfortunately, ceramics are not very strong physically andare prone to cracking and chipping if they are mishandled. In spite ofthe physical weakness of ceramics, they often must be used due to theirsuperior electrical and thermal characteristics. This poses a difficultproblem of properly mounting the connectors in their insulated housingswithout damage to the housings or danger of displacing the connectorsfrom the housings.

In the prior art female connectors with which I am familiar thecontacting surfaces have been normally spring loaded into engagementwith one another to secure positive gripping contact with maleconnectors. This often has made insertion of male connectors difiicult,has tended to dislodge their cooperating connectors from theirrespective housings, and has resulted in only line contact between themale and female connectors.

The general object of this invention is to provide a new or improvedelectrical socket construction.

A further object of this invention is to provide a socket constructionwherein the female connector has a large contact area.

Another object of this invention is to provide a socket constructionwherein the female connector has contacting surfaces which are parallelto one another when engaging a male connector.

A more specific object of this invention is to provide, in one form ofmy invention, an improved socket construction wherein the femaleconnector has contacting surfaces which at all times are substantiallyparallel.

A further object of this invention is to provide a socket constructionhaving a female connector into which a male connector may be insertedwith utmost ease.

Yet another object of this invention is to provide a socket connectionhaving improved and simplified means for mounting a female connector inan insulating hous- This invention contemplates achieving the foregoingobjects and other objects and advantages by the provision of a socketconstruction wherein a female connector is mounted in an insulating,preferably ceramic, housing. The connector is provided with opposedcontacting sur- 'the T-shaped cross section lying on the outside.

Patented Sept. 4, 1956 Ice faces of considerable extent which, in oneembodiment of the invention, are substantially parallel throughout theirextent at all times, either with a male connector inserted or not, andin another embodiment are spring biased toward one another and are urgedinto parallelism by a male connector for large surface area contacttherewith. The large, parallel contacting areas insure adequate contactwith a male connector, while the parallelism of the surfaces, coupledwith their normal parallelism in operation, facilitates insertion of amale connector into the female connector. The female connector takes theform of a clip which snaps into place in a recess in an insulatinghousing without the necessity of any fasteners which would tend to chipor crack a ceramic housing. The female connector is provided withportions bearing against the insulating housing which positivelymaintain the contacting areas substantially in parallelism with a maleconnector inserted.

Other and further objects and advantages of the present invention willbe apparent from the ensuing description when taken in connection withthe accompanying drawings, wherein:

Fig. 1 is a plan view partially in section and with certain parts brokenaway illustrating my improved socket construction and a plug cooperabletherewith;

Fig. 2 is an end view of the socket construction as taken along the line2-2 of Fig. 1;

Fig. 3 is a cross-sectional view of the socket construction with a plugabout to be inserted thereinto, and taken along the line 3-3 of Fig. 1;

Fig. 4 is a View similar to Fig. 3 showing the plug in fully insertedposition with the male and female connectors in cooperative engagement;

Fig. 5 is a cross-sectional view through the socket taken along the line55 of Fig. l; and

Fig. 6 is a perspective view of the female connector.

Referring now in greater particularity to the figures, and first to Fig.1, there will be seen my improved socket construction 10 and a plug 12cooperable therewith. The socket construction 10 includes an insulatingbase or housing 14 preferably formed of ceramic material such asporcelain. The ceramic base or housing 14 is substantially T-shaped incross section as may be seen in Figs. 3 and 4. The major portion of thehousing is adapted to be inserted into an aperture in a wall or the like16 with the peripheral flange 18 forming the arms of The flange 18 isprovided with a plurality of recesses 20 for accommodating the heads ofscrews 22 or the like which extend through the flange 18 and into thewall or the like 16 for mounting the socket.

The ceramic or insulating housing 14 is provided with a plurality ofparallel, elongated openings 24 which extend through the housing fromfront to back and are generally rectangular in cross section as may beseen in Fig. 5. The openings 24 are provided at their front ends withprojections or teeth 26 having beveled front edges 28 for facilitatinginsertion of a male connector, and having square shoulders 30 at therear thereof for retaining the female connector in place as will beapparent later.

Each opening 24 is further enlarged by a pair of longitudinal grooves orrecesses 32 extending throughout a substantial portion of the length ofthe openings 24. The grooves 32 along with the restrictions at the frontends of the openings formed by the teeth 26 impart a cross-shapedappearance to the openings when viewed from the front of the socket asin Fig. 2.

The female electrical connectors fit in the apertures 24 and aregenerally designated by the numeral 34. Each connector 34 is made ofsheet metal, preferably stainless steel, and comprises a U-shapedportion having parallel side walls 36 interconnected by a bight portion38. As

r 2,762,026 V Y may be seen in Figs.'3- and 4 and the walls 36 areadapted to abut. the, corresponding interior surfaces. of. the apentures 24.

The walls 36 continue integrally as diagonally inward- 1y directedsections-"38, which in turn continue integrally as parallel, spacedapart arms 40 adapted'toembrace-the male connectors asv will be apparenthereinafter. The outer ends of the arms 40 are outwardly deflected as at42 and are adapted to abut both the shoulders 30 to position theconnector 34 in its corresponding opening 24 and the side wall of the.opening to prevent spreading apart of the arms 40. i

A pair of rearwardly extending spring legs 44 is struck out of the arms40. The 'legs44 at'theforward ends thereof are integral with thedeflected portions- 42 of the arms and diverge outwardly therefrom in asmooth curve asat 46. The legs 44- reach ar'naximum separation at 43-atwhichpoint they are spaced apartslightly greater than the width of anopening 24. The. legs then curve inward ly again as at 50, and finallyoutwardly to from free tips or end sections 52. V

The legs 44 project part way into the grooves 32. while the free tips orend portions 52v abut the shoulders formed between the grooves 32 andthe sides of each opening to' prevent retraction of a connector after ithas.

been inserted into its corresponding opening 24. The/ complex curvedconfiguration of the legs 44 insures that the ends 52 thereof will standoutwardly of' the walls 36 for firm anchoring of the connector 34 inplace without having the ends .52 urged 'apart with such great force asto make insertion of the connector'into its. correspondingopening-24 ofthe housing 14 difficnlt age the housing;

The bight portion 38 of the connector 34 is. formed with a centralopening 54 having an extruded section or neck 56 surrounding it andprovided .on its inner surface with screw threads for receipt of a screw58. adapted I to clamp a connecting wire 60 against the bight portion 38of the connector. The free edges: of each bight portion 38 preferably.are. formed with rearwardly directed flanges 62 (omitted from the frontedge in Figs; 3 and 4 for clarity of illustration) to prevent the wire.60 from moving outwardly from beneath the head of the screw 58.

In Figs. 1, 3, and 4- there is shown a plug 12 cooperable with thesocket 10. The plug 12 comprises a ceramic or other insulating base orhousing 64 carrying a plurality of sheet metal prongs or electricalconnectors 66 which likewise can be formed of stainless steel. The maleconor likely to damnectors 66 are in the form of flat strips of materialwhich may be straight throughout their extremities or which.

may be twisted 90 as illustrated at 68, It will be understood that thefemale connectors 34 are oriented similarly to the male connectors 66.Twisting'or rotating one or more pairs of cooperating connectors insuresthat the plug 12 can be plugged into .the socket 10 in only one possibleposition, thus insuring proper connections. I

The male connectors or prongs. ,66 are provided. with dimples or struckout portions 70 (Figs. 3 and 4) fitting in recesses 72 in the insulatinghousing 64 and which may serve to aid .in positioning the maleconnectors in the housing. The housing 64 is provided with suitablerecesses 74exposing the rear ends of the male connectors or prongs 66.The rear ends are suitably apertured and threaded for receipt of screws76 for anchoring .connecting' wires 78. 2

Ceramic products such as the housing herein disclosed cannot always becontrolled economically to very close tolerances in production.Accordingly, I have found that it is sometimes necessary or desirabletoform the clip or female. connector to compensate for individualvariations in housings. A clip of this type is shown in Fig. 1 withapart of the housing broken away for clarity of illustration. This clipor female connector is generally identified by the numeral 34a and issimilar to the con Hector previously disclosed except that the arms 40aare angled toward one another. When the connector 34:: is

inserted in housingme legs. 44a, which diverge from.

the arms 40a more than in the previously disclosed embodiment, bias thearms 40a toward one another to bring.

them into line contact at the bases of the outwardly deflected armportions 42a. When a male connector is inserted the arms 40a are spreadinto parallelism against the spring force of the legs, 44:: so that alarge surface area of contact is obtained substantially independently ofthe size of the opening 24 in the housing;

It will be seen particularly from an inspection of Figs.

3 and 4 that the parallel arms 49 provide a large area of contact withthe male connector, thus positively avoiding burning, pitting, andgeneral overheating. The initial configuration of the. female connector34 is such that only the flexible legs 44 need be temporarily deformedin sliding each of the female connectors into its corresponding opening24 in the base or housing 14, and these legs do not exert. a.suflicientoutward force to tend to damage. the

housing during the insertion. After insertion, the legs 44a. in oneembodiment of the. invention bias the. arms; into line contact, while inthe other embodiment the legs. 44 do not: exert a sutficicntoutwardforce to tend'to force the arms 40.v toward one. another out ofparallelism. In

both forms of :the invention the dimensions. of the .con-

nectors are chosen so that. they and the abutment of the:

walls 36 and the outwardly deflected arm portions 42:vagainsttheinterior walls of each opening 24 tend to main-.-

tain. thev arms 40. and 40a in parallelism with a male connector 66inserted. between them and spreadinggthem apart very slightly.

' The beveled: front surfaces 28, of the. teeth26 serve to centralizeeach .male connector 66 to a considerable; extent, while. the outwardlydeflected arm ends. or portions. 42 complete :the centralization. 1Comparatively little effort; is needed in inserting av male connector.Thev out-- ward'ly deflected tips .52. of the legs 44 prevent. movementof a female connector fromits opening or recess; during insertion of amale connector while the outwardly deflected armsor tips 42 preventmovement. of

lating housing having an .elongated opening-therein, said housing,further havingv apairrof elongated recesses lying along oppositesidcs ofsaidopening and in open commun cation therewith, said.v recesses beingshorter than said. opening and forminginterior shoulders therewith, a

pair of oppositely disposed projections on said. housingextendingriutosaid opening at the front thereof and having outer beveled surfacesfacilitatingv insertion of a male connector into said opening, saidprojectionsv having interior shoulders arranged oppositely of therecess. shoulders; and a femalezconnector' in said opening, saidconnector being in the form of a sheet metal clip having means providingopposed substantially fiat contact sur- 7 I faces, said contact surfacesnormally being parallel to one another and adapted toengage acooperating male connector over a substantial area, said contact surfacedefining means having outwardly diverging ends engaging behind saidprojection shoulders and engaging opposite walls of said opening, a pairof parallel side wall portions spaced .apart'farther than said contactsurfaces and en gaging the opposite walls of said opening, and beingconnected to the means providing the contact surfaces by diagonal braceportions, the parallel walls and outwardly diverging ends engagingopposed walls of said opening I maintaining said contact surfaces at alltimes in parallel:

ism, and a pair of spring members struck from the means providing thecontact surfaces and extending sinuously outwardly therefrom in saidrecesses and having outwardly extending free ends engaging said recessshoulders, the free ends engaging said recess shoulders and theoutwardly diverging ends engaging said projection shoulders anchoringsaid female connector in said opening.

2. An electric socket construction comprising an insulating housinghaving an elongated opening therein, said housing further having anelongated recess lying along one side of the opening and in opencommunication therewith, said recess being shorter than said opening andforming an interior shoulder therewith, a pair of oppositely positionedprojections on said housing ex tending into said opening at the frontthereof and having outer beveled surfaces facilitating insertion of amale connector into said opening, said projections having interiorshoulders arranged oppositely of and confronting the recess shoulders,and a female connector in said opening, said connector being in the formof a generally U-shaped sheet metal clip having substantially flat legportions providing parallel, opposed, contact surfaces adapted to engagea cooperating male connector over a substantial area, said femaleconnector having outwardly diverging ends on the fiat leg portionsengaging behind the projection shoulders and engaging opposite walls ofsaid opening, a pair of substantially flat leg portions between saidcontact surfaces and the bight of said female connector positionedfarther apart than the contact surface providing flat leg portions andinterconnected therewith by diagonal leg portions, the second mentionedpair of flat leg portions engaging opposite walls of said opening andcoacting with said outwardly diverging ends to maintain said contactsurfaces at all times in parallelism, and a spring member struck fromone of the legs of the female connector, said spring member beingattached to one of the outwardly diverging ends and extending outwardlytherefrom and back along a contact providing leg portion into engagementwith the recess shoulder, whereby, in cooperation with the outwardlydiverging ends engaging the projection shoulders to anchor said femaleconnector in said opening.

3. A female connector as set forth in claim 2, wherein the bight isprovided with flanges on its margins projecting in a direction away fromthe flat leg portions behind the projection shoulders which serve toreinforce said bight portion, and with an aperture for receipt of ascrew for clamping a connecting wire against said bight between saidflanges.

References Cited in the file of this patent UNITED STATES PATENTS1,700,831 Downing Feb. 5, 1929 1,841,736 Jones Jan. 19, 1932 2,034,966Weich Mar. 24, 1936 2,223,231 Smith Nov. 26, 1940 2,259,207 Hunt Oct.14, 1941 2,296,631 Doane Sept. 22, 1942 2,360,917 Wade Oct. 24, 19442,384,287 Drury Sept. 4, 1945 2,664,552 Ericsson et al. Dec. 29, 19532,691,147 Sutton et al Oct. 5, 1954

